Surveying instrument



May 15, 1934. w. L. EGY ET AL 1,958,512

SURVEYING INSTRUMENT Filed Sept. 10. 1951 2 Sheets-Sheet 2 M d, Gttornegsl Patented May 15, 1934 UNITED STATES SURVEYING INSTRUMENT Willard L. Egy and Charles E. Smart, Troy, N. Y.,

assignors to W. & L. E. Gurley,

Troy, N. Y., a

corporation of New York Application September 10, 1931, Serial No. 562,158

7 Claims.

This invention relates to surveying instruments, and particularly to an improved form of Vernier mounting for transits.

1n transits of the prior art, it has been customary'to form the top plate carrying the standards in a single piece, the plate having an outer rim terminating in a flange depending below and outside of the outer face of the lower plate or limb. The top plate carries on its under face, two verniers placed diametrically opposite each other and exposed to view through cover glasses provided in openings in this plate. The position of these verniers is such that they are adjacent to the surface of the limb carrying the graduated circle, thereby making it possible to read the Vernier and determine the angular position of the top plate.

Since the verniers in such construction are mounted on the lower side of the top plate, and since the screws are inserted through the Vernier and threaded into the top plate, the lower plate which carries the graduated limb underlies the verniers and the heads of the screws and precludes adjustment while the transit frame and limb are assembled. It is consequently necessary to withdraw the spindle which carries the top plate from the quill which carries the lower plate and graduated limb, and adjust the verniers while the latter are out of coactive relation with the graduated limb, then replace the parts and test for accuracy of the adjustment. The instrument maker must proceed by trial and error, repeating the operation above described until the desired result is attained. As the spindle bearing must be most carefully cleaned prior to each assembly, the operation is slow, tedious and expensive.

In instruments embodying the present invention., the verniers are mounted on the upper side of the top plate, preferably on the upper side of a peripheral flange formed on the plate, and are attached by screws which pass through the verniers and are threaded into the plate, or said flange. They are protected by a removable cover plate attached to the top plate and carrying the usual cover glasses. Removal of the cover plate gives direct access to the screws and verniers and permits the latter to be adjusted while in coactive relation to the graduated limb. Consequently, the only dismounting operation is that incident to the removal and replacement of the cover plate.

A11 necessary adjustments can be completed and the Vernier plates fixed to their mounting,

before the cover ring is replaced. An arrangement of this sort not only saves time and promotes accuracy, but it avoids the possibility of injury to the parts by repeated assembling and disassembling, such as is necessary in adjusting the verniers of the prior art The invention will be better understood by reference to the accompanying specification, when read in connection with the drawings, in which,-

Fig. l is a Vertical sectional view through the top and bottom plates of 'a transit, a portion ofr the standards being broken away, and the being taken through the Vernier plates;

Fig. 2 is a partial vertical section through the top and bottom plates,` showing the manner of securing the cover ring to the top plate, and its relation to the limb;

Fig. 3 is a fragmentary plan View of the assembled plates, with parts broken away to show the graduations on the limb and one Vernier plate;

Fig. 4 is a detail sectional View on line 4-4 of Fig. 3, showing the adjusting means for the vernier plates;

Fig. 5 is aplan view of the cover ring removed from the instrument; and

Figs. 6 and '7 are sectional Views of the cover ring on lines 6-6 andv 7--7, respectively, of Fig. 5.

For purposes of illustration, the invention will be described as commercially embodied in conjunction with a novel form of transit frame desection scribed and claimed in the patent of Egy, Day

and Smart, No. 1,923,193', granted Aug. 22, 1933.

In this frame the Vertical axis spindle and the central portion of the top plate are constructed integrally, and the peripheral portion of the top plate is constructed as a ring integral with the telescope standards. These two parts are permanently connected by a threaded shrink joint to form what is in effect a one piece frame. No claim is here made to the construction of the frame except in combination with features here disclosed. The invention is applicable to other types of transit frame including those of conventional rnulti-piece construction.

The reference character 8 designates the cenltral portion of the top plate of the transit, and 11 indicates the spindle formed integrally therewith. The spindle is formed with the usual tapered journal which turns in the tapered quill, the quill being designed to turn in a bearing in the leveling head as is standard practice. Connected to the central portion 8 of the top plate, by threads 10, is the ring 12 which carries the telescope standards partially shown at 9. The ring 12 carries below its upper surface, a ange or rim 13, on whose upper face are mounted the verniers hereinafter described, and the cover ring 14.

Ring 14 is secured to the lip 13 by screws 15, as shown in Fig. 2, and is provided with the usual Vernier openings 20 containing cover glasses 16. The cover ring 14 carries an external depending annular flange 35, which projects well below the graduated surface of limb 22. By reference to Fig. 5, it will be observed that the screws flac enter threaded openings 36 in spaced lugs 33 formed on the underside of ring 14 and connected by flanged portions 34, and that these portions 34 and lugs 33 rest on the lip 13 when the ring 14 is in place.

The openings are disposed at points spaced 180 apart in the ring 14, and mounted on the lip 13 underneath each of these openings is a Vernier plate 17. The plates 17 are secured to the lip 13 by screws 18, accessible when ring 14 is removed, and cooperating with enlarged screw openings 19 in the plate 17 to allow necessary adjustments of the plates to be made.

The Vernier plates 17 are provided with the usual Vernier graduations 21, which, when the parts are assembled, move in close juxtaposition to the graduated surface 23 of lower plate or limb 22. As here shown, this limb is carried by a flange 24 on the tapered quill 25, and thev two are secured together by screws 26 accessible Vfrom the top when the transit frame is removed.

The iiange 24 also carries a collar 27 threaded at 28 for cooperation with the usual tangent screw adjusting means, and this collar is secured to the flange 24 by screws 29. Flange 24 also has an upstanding ilange 31 which carries a plurality of threaded adjusting screws 32, only one of which f is shown in Fig. 1for centering the limb 22 with the vertical axis of the instrument.

In assembling the instrument, the lower plate or limb can rst be assembled by securing collar f 27 and limb 22 to the flange 24. Thereafter, the

transit frame may be mounted in position by inserting the spindle on the quill,` as shown in Fig. l. Before the cover ring 14 is applied, the Vernier plates 17 are mounted on the lip 13, but

rthe screws 18 are not tightened until the parts are finally positioned.

If the limb 22 is not properly centered, the transit frame may beremoved and adjustment made by means of screws 32, screws 26 being ,sufciently loosened to permit this adjustment.

Thereupon, the transit frame is replaced and the zero point of each Vernier with respect to the zero points of graduations 23 is observed. If these points do not coincide properly, the plates 17V can be tapped slightly until exact alignment is secured, and then the screws 18 tightened to secure the plates xedly to lip 13. Thereupon, the cover ring 14 is slipped over the top of the instrument and dropped in place, with lugs 33 and flanges 34 engaging the lip 13. The ring is so positioned that the cover glasses 16 are over the verniers, and the openings 36 in lugs 33 are in line with the screw openings in lip 13.

It will be understood that the verniers may be adjusted with the transit frame in position, but that this transit frame must be raised for the insertion of screws 15 to secure the cover plate to lip 13, after the Vernier plates have been fixed. This removal, however, can be accomplished without any possibility of the Vernier plates being disturbed from their properly adjusted positions, and the transit frame 8 can be replaced as soon as these screws 15 are tightened.

The applicants believe that they are the iirstY to provide a transit with a removable cover ring of this character, so as to permit adjustment of the Vernier plates while the latter are in coactive relation with the graduated limb, and it is desired that the broadest possible interpretation be given to the claims presented, without limitation to theV particular embodiment shown and described.

What is claimed is:

1. In a transit, the combination of a frame mounted to turn on a vertical axis; a graduated limb mounted to turn concentrically with said frame; at least one Vernier plate adjustably mounted on top of a horizontal surface at the periphery of said frame and adapted to coact with said limb; at least one clamping screw eX- tending downward through said Vernier and Ythreaded into said horizontal surface of the lower face of said body and adjacent the innen? periphery thereof, said lugs being provided with openings to receive attaching means for said ring.

3. In a transit the combination of a frame rotatable on a vertical axis, said frame includ'- ing a peripheral annular lip; a pair of Vernier plates movably mounted in spaced relation on the upper face of said lip; means for adjustably fixing said Vernier plates in position, said means being accessible when the upper face of said lip' is exposed; and removable covering means having transparent portions, said covering means being attached to said frame, overlying said lip and serving to enclose said Vernier plates and said plate fixing means.

4. In a transit, a frame having a horizontal projecting annular lip on its outer face; a pair of spaced VernierV plates adjustably mounted on the top of said lip; and a removable cover ring secured to said lip and enclosing said plates, said ring containing openings overlying said Vernier plates to render the Vernier scale Visible when said ring is in place.

5. In a transit, a frame comprising a top plate and an outer ring intimately united in threaded relation; an annular projecting lip on the bottom edge or" said ring; a pair oi spaced Vernier plates on said lip and adjustably related thereto; a cover ring movable with said frame and enclosing said plates, said ring containing sight open-` ings registering with said vernier plates; and an outer depending flange on said cover ring.

6. In a transit, a frame having an annular lip projecting radially therefrom; a graduated limb encircling said lip; a pair of adjustable Vernier plates on the upper face of said lip in juxtaposition to said limb; clamping screws extending downward through said plates and threaded into said lip; and a removable cover ring secured to said frame and enclosing said plates, said clamping screws and said limb, said ring containing sight openings registering with saidV plates.

7. In a transit, a frame having a radial lip projecting therefrom; a pair of Vernier plates vadjustably secured on the top of said lip and having their outer edges concentric with the outer edge of said lip; a graduated limb encircling said lip and coacting with said Vernier plates; and a removable cover ring carried by said frame and enclosing said Vernier plates and said limb, said plates being accessible for adjustment when said ring is removed.

WILLARD L. EGY.

CHARLES E, SMART. 

